kernel/linux.git/fs/fuse/control.c, branch linux-5.11.y

fuse: split fuse_mount off of fuse_conn

2020-09-18T13:17:41+00:00

We want to allow submounts for the same fuse_conn, but with different superblocks so that each of the submounts has its own device ID. To do so, we need to split all mount-specific information off of fuse_conn into a new fuse_mount structure, so that multiple mounts can share a single fuse_conn. We need to take care only to perform connection-level actions once (i.e. when the fuse_conn and thus the first fuse_mount are established, or when the last fuse_mount and thus the fuse_conn are destroyed). For example, fuse_sb_destroy() must invoke fuse_send_destroy() until the last superblock is released. To do so, we keep track of which fuse_mount is the root mount and perform all fuse_conn-level actions only when this fuse_mount is involved. Signed-off-by: Max Reitz Reviewed-by: Stefan Hajnoczi Signed-off-by: Miklos Szeredi

treewide: Remove uninitialized_var() usage

2020-07-16T19:35:15+00:00

Using uninitialized_var() is dangerous as it papers over real bugs[1] (or can in the future), and suppresses unrelated compiler warnings (e.g. "unused variable"). If the compiler thinks it is uninitialized, either simply initialize the variable or make compiler changes. In preparation for removing[2] the[3] macro[4], remove all remaining needless uses with the following script: git grep '\buninitialized_var\b' | cut -d: -f1 | sort -u | \ xargs perl -pi -e \ 's/\buninitialized_var$([^$]+)\)/\1/g; s:\s*/\* (GCC be quiet|to make compiler happy) \*/$::g;' drivers/video/fbdev/riva/riva_hw.c was manually tweaked to avoid pathological white-space. No outstanding warnings were found building allmodconfig with GCC 9.3.0 for x86_64, i386, arm64, arm, powerpc, powerpc64le, s390x, mips, sparc64, alpha, and m68k. [1] https://lore.kernel.org/lkml/20200603174714.192027-1-glider@google.com/ [2] https://lore.kernel.org/lkml/CA+55aFw+Vbj0i=1TGqCR5vQkCzWJ0QxK6CernOU6eedsudAixw@mail.gmail.com/ [3] https://lore.kernel.org/lkml/CA+55aFwgbgqhbp1fkxvRKEpzyR5J8n1vKT1VZdz9knmPuXhOeg@mail.gmail.com/ [4] https://lore.kernel.org/lkml/CA+55aFz2500WfbKXAx8s67wrm9=yVJu65TpLgN_ybYNv0VEOKA@mail.gmail.com/ Reviewed-by: Leon Romanovsky # drivers/infiniband and mlx4/mlx5 Acked-by: Jason Gunthorpe # IB Acked-by: Kalle Valo # wireless drivers Reviewed-by: Chao Yu # erofs Signed-off-by: Kees Cook

convenience helper: get_tree_single()

2019-07-05T02:01:58+00:00

counterpart of mount_single(); switch fusectl to it Signed-off-by: Al Viro

fuse: Convert fusectl to use the new mount API

2019-04-24T15:05:07+00:00

Convert the fusectl filesystem to the new internal mount API as the old one will be obsoleted and removed. This allows greater flexibility in communication of mount parameters between userspace, the VFS and the filesystem. See Documentation/filesystems/mount_api.txt for more information. Signed-off-by: David Howells Signed-off-by: Miklos Szeredi

fuse: clean up aborted

2019-02-13T12:15:14+00:00

The only caller that needs fc->aborted set is fuse_conn_abort_write(). Setting fc->aborted is now racy (fuse_abort_conn() may already be in progress or finished) but there's no reason to care. Signed-off-by: Miklos Szeredi

fuse: introduce fc->bg_lock

2018-09-28T14:43:22+00:00

To reduce contention of fc->lock, this patch introduces bg_lock for protection of fields related to background queue. These are: max_background, congestion_threshold, num_background, active_background, bg_queue and blocked. This allows next patch to make async reads not requiring fc->lock, so async reads and writes will have better performance executed in parallel. Signed-off-by: Kirill Tkhai Signed-off-by: Miklos Szeredi

fuse: add locking to max_background and congestion_threshold changes

2018-09-28T14:43:22+00:00

Functions sequences like request_end()->flush_bg_queue() require that max_background and congestion_threshold are constant during their execution. Otherwise, checks like if (fc->num_background == fc->max_background) made in different time may behave not like expected. Signed-off-by: Kirill Tkhai Signed-off-by: Miklos Szeredi

fuse: use READ_ONCE on congestion_threshold and max_background

2018-09-28T14:43:22+00:00

Since they are of unsigned int type, it's allowed to read them unlocked during reporting to userspace. Let's underline this fact with READ_ONCE() macroses. Signed-off-by: Kirill Tkhai Signed-off-by: Miklos Szeredi

fuse: fix control dir setup and teardown

2018-05-31T10:26:10+00:00

syzbot is reporting NULL pointer dereference at fuse_ctl_remove_conn() [1]. Since fc->ctl_ndents is incremented by fuse_ctl_add_conn() when new_inode() failed, fuse_ctl_remove_conn() reaches an inode-less dentry and tries to clear d_inode(dentry)->i_private field. Fix by only adding the dentry to the array after being fully set up. When tearing down the control directory, do d_invalidate() on it to get rid of any mounts that might have been added. [1] https://syzkaller.appspot.com/bug?id=f396d863067238959c91c0b7cfc10b163638cac6 Reported-by: syzbot Fixes: bafa96541b25 ("[PATCH] fuse: add control filesystem") Cc: # v2.6.18 Signed-off-by: Miklos Szeredi

fuse: return -ECONNABORTED on /dev/fuse read after abort

2018-03-20T16:11:44+00:00

Currently the userspace has no way of knowing whether the fuse connection ended because of umount or abort via sysfs. It makes it hard for filesystems to free the mountpoint after abort without worrying about removing some new mount. The patch fixes it by returning different errors when userspace reads from /dev/fuse (-ENODEV for umount and -ECONNABORTED for abort). Add a new capability flag FUSE_ABORT_ERROR. If set and the connection is gone because of sysfs abort, reading from the device will return -ECONNABORTED. Signed-off-by: Szymon Lukasz Signed-off-by: Miklos Szeredi